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The novice can solve the frequency converter common fault diagnosis and processing.(6)
- May 29, 2018 -

1.6 contactor damage

1.6.1 contactor damage judgment

(1) in case of serious overcurrent short-circuit at the later stage of the converter, such as the explosion of the inverter bridge module, explosion of the filter electrolytic capacitor, etc., it shall be checked whether the contactor is affected.Common damages include contact ablation, sintering, and contact deformation of plastic parts.

(2) in a small number of contactors, the control line will be broken and completely motionless.

1.6.2 cause of damage

(1) there is short circuit in the back stage, and the overcurrent fault causes the contact ablation.

(2) the quality of the wire wrap is not good, and the wire wrap burns down and breaks the wire, but cannot be absorbed.

(3) for contactor with electronic circuit, it will be unable to operate due to damage of electronic circuit, so it is better not to use such contactor.

(4) damaged by the explosion flame.

1.6.3 replacement

(1) select products of the same type, same size and same voltage of wire wrap for replacement. If the model is different, the performance, size and voltage should be the same.

(2) if there is an old contactor, it can be repaired by replacing the internal parts, but it must be properly assembled according to the original internal assembly.

(3) for the contact with no serious ablation, it can continue to use fine sand cloth to carefully sand and light.

(4) as the contacts have to flow through a large current, the copper strips and wires connected with the screws must be firmly tightened to reduce heat.

1.7 damage of printed circuit board

1.7.1 damage judgment of printed circuit board

(1) ruled out after failure of main circuit devices, such as can't make the inverter to work properly, the most simple and effective judgment is to remove the PCB have a look at the positive and negative of discoloration of element, color printing line, local burn out.

(2) the printing plate on the general frequency converter mainly includes drive plate, main control board and display board. According to the fault performance characteristics of the frequency converter, the method of changing plate is used to determine which board is defective.For other printing plate, such as absorption plate, GE plate, fan power plate, etc., because the circuit is simple and can be quickly detected by multimeter.

(3) when there is a circuit diagram, the printing plate shall check the voltage of each power source according to the diagram. The oscillograph shall be used to check the waveform of each point.When there is no circuit diagram, a comparison method is adopted to compare the same parts of several routes. The difference between the fault plate and the good plate can be found by comparing the fault plate and the good plate.

1.7.2 cause of damage to printing plate

(1) the quality and service life of components themselves cause damage, especially those with higher power, which is more likely to be damaged.

(2) the components are damaged by overheating or overvoltage, the transformer is cut off, the electrolytic capacitor is dry and leakage, and the resistance is changed at high temperature for a long time.

(3) corrosion of printing plate, breakdown of insulation, leakage of electricity and other damages caused by environmental temperature, humidity, water dew and dust.

(4) the components and printing lines on the driving plate are damaged due to module damage.

(5) due to the bad contact of the connector, the single-chip microcomputer and memory are invalid due to interference crystal vibration.

(6) the original program cannot work due to the user's own confusion.

1.7.3 maintenance of printing plate

(1) the maintenance of printing plate requires a circuit diagram, power supply, multimeter, oscilloscope, a full set of welding and disassembly tools, as well as accumulated experience, to find the damage relatively quickly.

(2) the surface of the printing plate is coated with protective paint and other coatings. When testing, it is necessary to contact the tested metal carefully with a needle pen to prevent misjudgment.As the components are prone to damage due to overheating and overvoltage, the following parts require high attention.

Switch power supply of the switch tube, switch transformer, overvoltage absorbing components, power device, pulse transformer, high voltage isolation optocoupler, over-voltage absorption or buffer absorption board and its subordinate element, charging resistance, field effect tube IGBT tubes, voltage regulator tube or voltage integrated circuit.

(3) PCB change may cause problems with different version, so if sure you want to change, depends on whether the plate number identification, such as inconsistent and the obstacles, to clear understanding to the manufacturers.

(4) the single chip microcomputer serial number is not the same as the internal procedures are different, some of the project may be in use as well as we did not, therefore, used as the confirmation process has a problem, you should ask manufacturer.

(5) due to interference, abnormal operation or protection of the frequency converter will occur.At this point, the anti-interference measures should be taken, in addition to the inverter overall considering anti-jamming (such as reactor with ac input/output and good radio interference suppression reactor, the output line and the circular, etc.), also can be in the power supply end of the PCB mounted by the circular and in-phase string around a few turns of wire form the so-called common mode rejection of reactor, up and down position for printed circuit board for electrostatic shielding, isolation and the external control line measure such as using shielded wire or twisted pair.

(6) PCB to electrify inspect after maintenance, now don't directly to the main loop of the inverter power, and to use the auxiliary power supply power for printed circuit board, using a multimeter to check voltage, waveform oscilloscope for observation, verify the complete can only be received after the main circuit debugging.